You have analog cameras, so you can't run them directly to the PC, but
Blue Iris will
pull the stream from most DVR's, so without knowing the brand, you will have to try it to find out.
For future cameras, you probably want to read this,
...
ipcamtalk.com
This is an intermediate / newbie guide for people just starting out looking for a surveillance setup. I know this setup might not be for everyone and there are many options. You can find a lot of this information in the
Wiki: IP Cam Talk Wiki | IP Cam Talk A great place to start in the Wiki...
ipcamtalk.com
For a Blue Iris PC, read the notes, and figure out how many cameras, and what resolution you would want.
This will let you know how much and what type of PC you will need to run it. Leave a little room for expansion.
Buy refurbished. Don't build or buy new. The most cost-effective Blue Iris computers are refurbished business-class systems such as "HP EliteDesk" and "Dell OptiPlex". You can usually get a good deal by searching [URL='http://www.ebay.com/']Ebay[/URL] for specific CPU model numbers, and...
ipcamtalk.com
It really makes sense to draw out the location and draw in what you want covered, and where you
have to put cameras to cover that area.
Calculate the focal point of a camera to help determine the best size lens to order. Save & view your results later.
ipcamtalk.com
It works best to pick up a varifocal camera and place it in each location to figure what lens you need for each, or if you need a varifocal.